1. Field of the Invention
This invention relates generally to polygraph systems and methods; and more particularly to such apparatus or procedures that require no mechanical contact with the subject.
2. Nomenclature
Defining the bounds of this invention calls for clear understanding of relationships between these two discrete concepts:                “frequency shift” (or “frequency change”, or “change of frequency”) of a carrier of pulses; and        “change in frequency characteristics” (or “frequency band change”, or “change of bandwidth”) of such a carrier.These relationships are taken up in this subsection 2.        
In patent matters it has long been recognized by the High Courts that a patent applicant “is entitled to be his own lexicographer”. This means, of course, that an inventor is permitted to define terms, for purposes of his application (and resulting patent if any) as the inventor prefers. Modern appellate decisions have extended this rule, even so far as to permit an applicant to define terms in ways that diverge from and indeed are even contrary to standard accepted meanings.
For purposes of this document, the phrase “frequency shift” (or “change”) shall be understood to encompass “change in frequency characteristics” (including e.g. “change of bandwidth”)—except where expressly otherwise indicated in the text (and except in this subsection “2. NOMENCLATURE” of this “BACKGROUND” section). Thus for example the concept of a frequency shift shall be understood to mean (a) literally, a change or shift in frequency as such, or (b) a change in bandwidth or other change in frequency characteristics, or (c) both.
This definition of “frequency shift” (or “frequency change”) conforms the language in this document to casual, informal jargon used by many scientists, engineers and technicians in this field. Such casual but ubiquitous usage, though possibly less than completely rigorous, was in fact part of the origin of language in certain of the appended claims, in this and the parent patent application. Hence this definition is consistent both with usage and (more importantly) with original concepts taught in the parent case.
In this document, wherever it is intended to isolate the concept of a shift in frequency, without encompassing any other sort of change in frequency characteristics, the text of this document recites either e.g. “frequency shift per se” or “frequency shift, literally”.
Also for purposes of this document the terms “scattering” or “backscattering”—both very generally synonymous with “return”—apply both to in-band return, at the same wavelength as is transmitted, and to Raman return at a different wavelength.
3. Related Art
The art of the popularly designated “lie detector” is a mature one and well known. In it, ordinarily a subject to be interrogated is attached to various sensors for measurement of heart rate, breathing rate, perhaps skin characteristics and body temperature, and sometimes other body parameters. This technology is generally effective and a helpful tool, although the legal system has been traditionally somewhat slow to accept it because of recognized susceptibility to both false positive results (i.e. incorrect apparent finding of a lie when the subject has actually been truthful) and false negative results (i.e. failure to detect an actual lie, or in other words an incorrect finding of truthfulness).
Polygraph testing and recording is either accompanied by or part of an interrogation of some kind, and in turn commonly accompanied by audio and sometimes video recording. Thus, to conduct a full examination, operation of the recording polygraph devices themselves is additive with respect to, for instance, a video camera with a sound track.
A drawback in conventional polygraphy is the need to attach the sensors before the examination and detach them afterward. Aside from the awkwardness of this procedure and the time consumed, some subjects are uncooperative or violent and may be dangerous to the operators of the equipment—while others may pose a hazard by virtue of highly communicable diseases such as AIDS, hepatitis and ebola.
Another difficulty with the conventional technology is the relatively high incidence of false positives due to a subject's nervousness about being connected to the apparatus and then questioned. A less-obtrusive system could significantly mitigate this problem.
Also it is well known that some subjects are able to suppress bodily response to stress (leading to false negatives), and others can generate voluntary variations and correlations (leading to a continuing stream of false positives) that mask response to stress. In effect the subject is lying not only to the questioner but to the machine as well.
The problem of unwitting false positives also is complicated by the problem of intentional false positives. These various effects degrade the reliability of all conventional polygraphic systems and techniques.
Not all polygraphy is related to criminal testimony. Some is potentially useful instead in hiring applicants for sensitive jobs such as intelligence, police and other security work—or even simply positions calling for a high degree of personal stability and trustworthiness, as for instance teachers, managers, pilots, bus drivers, medical and paramedical workers, and mass-transportation maintenance personnel.
In these areas it is unseemly to subject applicants to the indignity of attaching leads and sensors to the skin. In common situations where only one polygrapher is available, an additional issue of sexual impropriety or at least offensiveness may arise when a subject and a polygrapher are of opposite gender.
Also related to the characteristics of a polygrapher is the requirement for attention by a professional who is highly trained. A more highly automated system could reduce or eliminate the need for such advanced expertise—particularly if resulting primary data, without need for interpretation, could be used directly as evidence.
Results from conventional polygraphy do not appear to be sufficiently consistent for such use. This field accordingly would benefit from refinement of the technology to provide more reproducible results from test to test.
Finally, in most cases observation of a subject's body parameters is subject to considerations of civil liberties and personal privacy under the United States Constitution—and similar established policy worldwide; nevertheless, there are established circumstances under which such considerations are inapplicable or at least very severely attenuated. For example, it is understood that the law in much if not all of the United States accords to convicted felons while in prison a much lower degree of personal privacy than to citizens generally. Therefore it would be appropriate and desirable in such circumstances to have some means for monitoring vital signs without a subject's knowledge.
Accordingly it would be desirable to provide a form of polygraphic equipment and methodology requiring no such sensor attachment, and also amenable to a wider range of vital parameters through a single sensor module.
A heretofore-unrelated art is that of light detection and ranging—sometimes called “lidar” by analogy to radio detection and ranging, and its better-known acronym “radar”. Most conspicuously lidar has been used in large-scale aerial imaging, as in U.S. Pat. No. 5,467,122 of Bowker et al. directed to a streak-tube form of lidar for ocean-volume monitoring; but small- and even medical-scale applications are known as set forth in a related patent application of the same inventors, and to uses at a wide range of scales as disclosed in international application WO 97/18487 of Bowker et al.
The references just cited generally use a translating or scanning pulse source, with the receiver and transmitter substantially collocated. Through use of a streak-tube time resolver, they intrinsically map distance (“range”), between the transceiver and objects of interest, into position along one dimension (e.g. height) of a display screen—so that each pulse provides a sectional, two-dimensional image in a plane passing through the transceiver.
Due to the scanning or translation of the transceiver, successive pulses provide substantially parallel such individual sectional images. These can then be integrated visually or otherwise into, effectively, a three-dimensional image.
Another well-known form of streak-tube lidar avoids the translation of the transceiver, substituting a different kind of remapping by use of a fiber-optic prism with rows of fiber-optic pixels physically rearranged—so that an entire two-dimensional image can be presented to a streak tube as a single line (i.e. one-dimensional) image. The streak tube is then able to time-resolve motion within the entire image, based on a single laser pulse; but a computer reassembly of the image—with its motion—is required since an image would otherwise appear unintelligibly scrambled by the original action of the fiber remapper.
This technology is epitomized by well-known seminal patents of Knight and of Alfano. No fiber-optic remapper is needed in the scanning-transceiver systems; but the latter can acquire with a single laser pulse only a very small section of an entire three-dimensional image, whereas the remapper enables collection of an entire such image from each pulse.
In still another variant, sometimes called a “bistatic” configuration, the lidar transmitter and receiver are not collocated but rather are in quite different locations. Here the laser pulses reflected from a subject are distorted by the effectively ellipsoidal character of the wavefronts reaching the receiver.
Here too, a computer reconstruction of the image is needed if the application at hand calls for a natural-appearing picture. Bistatic streak-tube lidar configurations are analogous to the similarly separated source/receiver configuration of radar systems.
A streak tube, however, is only one example of devices suited for time-resolution in lidar systems. Other alternatives will be introduced later in this document.
These several forms of lidar have been used to measure the conformation of land, or other objects, either directly in view or through turbid media that obscure direct vision. To the best of our knowledge no connection has ever been suggested between lidar and polygraphy.
The three patent documents mentioned above, and all references cited therein, are wholly incorporated by reference into the present document. In particular this incorporation by reference shall include but not be limited to pictorial illustrations in those documents, which accordingly shall be regarded as directly presented in the present document.
As can now be seen, the related polygraphic art remains subject to significant problems, and the efforts outlined above—although praiseworthy—have left room for considerable refinement.